CT scans may increase risk of brain cancer – Study

A new study published in the Journal of the National Cancer Institute, Maryland, USA, suggested that computed tomography scans, commonly used in medical imaging, may increase the risk of brain tumours.

According to sciencedaily.com, CT scans have increased dramatically over the last two decades and have greatly improved diagnostic capabilities which improve clinical outcomes but they deliver higher radiation doses than other tests.

Therefore, radiation protection is a concern, especially among children, who may receive higher radiation doses as they are more susceptible to radiation-related malignancies than adults and have more time to show effects from the potential risk.

The researchers noted that the most common tumour caused by radioactivity among children and young adults was leukaemia and brain tumours. They also evaluated leukaemia and brain tumour risks following exposure to radiation from CT scans in childhood.

The study was carried out on 168,394 Netherland children who received one or more CT scans between 1979 and 2012. The researchers obtained cancer incidence and vital status by record linkage. They surveyed all Netherland hospital-based radiology departments to ascertain eligibility and participation.

In the Netherlands, paediatric CT scans are only performed in hospitals as overall cancer incidence was 1.5 times higher than expected.

For all brain tumours combined, and for malignant and non- malignant brain tumours separately, dose-response, the study observed the relationships which were observed with radiation dose to the brain.

Relative risks increased between two and four for the highest dose category as the researchers observed no association for leukaemia. Radiation doses to the bone marrow where leukaemia originates were low.

They, however, caution that this pattern of excess cancer risk may be partly due to confounding by indication because the incidence of brain tumours was higher in the cohort than in the general population.

CT scans are sometimes used to identify conditions associated with an increased tumour risk; the reason these children had CT scans may be associated with their risk of developing cancer.

“Careful justification of paediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks,” he noted.

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